Android 基础知识系列之 ContentProvider
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ContentProvider是Android四大组件之一，其本质上是一个标准化的数据管道，它屏蔽了底层的数据管理和服务等细节，以标准化的方式在Android 应用间共享数据。用户可以灵活实现ContentProvider所封装的数据存储以及增删改查等，所有的ContentProvider 必须实现一个对外统一的接口（URI）。
本篇文章主要介绍 Android 开发中的部分知识点，通过阅读本篇文章，您将收获以下内容:
ContentProvider
获取联系人信息的方法
获取短信内容的方法
ContentResolver 内容解析者
ContentObserver 内容观察者
ContentProvider ContentResolver ContentObserver 三者关系
1. ContentProvider 实现
ContentProvider 继承关系
java.lang.Object
↳ android.content.ContentProvider四大组件之一，必须在Androidmainfest.xml 中注册
<provider android:name="com.programandroid.ContentProvider.CustomContentProviderMethod"
android:authorities="ProgramAndroid"
android:exported="true" />注意 : URI 中的元素
继承 ContentProvider 实现增删改查等方法
package com.programandroid.ContentProvider;import android.content.ContentProvider;import android.content.ContentUris;import android.content.ContentValues;import android.content.UriMatcher;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;import android.support.annotation.Nullable;/*
* ContentProviderMethod.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/public class CustomContentProviderMethod extends ContentProvider { private SQLiteDatabase db; private static final String MAUTHORITIESNAME = "ProgramAndroid"; private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH); private static final int PERSON = 1; private static final int PERSON_NUMBER = 2; private static final int PERSON_TEXT = 3; private static final String TABLE_NAME = "table_person"; // 构建URI
static { // content://programandroid/person
matcher.addURI(MAUTHORITIESNAME, "person", PERSON); // # 代表任意数字content://programandroid/person/4
matcher.addURI(MAUTHORITIESNAME, "person/#", PERSON_NUMBER); // * 代表任意文本 content://programandroid/person/filter/ssstring
matcher.addURI(MAUTHORITIESNAME, "person/filter/*", PERSON_TEXT);
} @Override
public boolean onCreate() {
DBHelper helper = new DBHelper(getContext()); // 创建数据库
db = helper.getWritableDatabase(); return true;
} @Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) { // 过滤URI
int match = matcher.match(uri); switch (match) { case PERSON: // content://autoname/person
return db.query(TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder); case PERSON_NUMBER: break; case PERSON_TEXT: break; default: break;
} return null;
} @Nullable
@Override
public Uri insert(Uri uri, ContentValues values) { // 过滤URI
int match = matcher.match(uri); switch (match) { case PERSON: // content://autoname/person
long id = db.insert(TABLE_NAME, null, values); // 将原有的uri跟id进行拼接从而获取新的uri
return ContentUris.withAppendedId(uri, id); case PERSON_NUMBER: break; case PERSON_TEXT: break; default: break;
} return null;
} @Override
public int delete(Uri uri, String selection, String[] selectionArgs) { return 0;
} @Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) { return 0;
} @Nullable
@Override
public String getType(Uri uri) { return null;
}
}提供对外提供操作的数据库方法
package com.programandroid.ContentProvider;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;/*
* DBHelper.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/public class DBHelper extends SQLiteOpenHelper { private static final String DB_NAME = "persons.db"; private static final int DB_VERSION = 1; private static final String TABLE_NAME = "table_person"; private static final String ID = "_id"; private static final String NAME = "name"; public DBHelper(Context context) { super(context, DB_NAME, null, DB_VERSION);
} @Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE " + TABLE_NAME + "(" + ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL" + "," + NAME
+ " CHAR(10) )";
db.execSQL(sql);
} @Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}其他APK 访问此ContentProvider 数据库的方法
public class MainActivity extends Activity { private String uri = "content://ProgramAndroid/person"; private EditText mEditText;
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mEditText = (EditText) findViewById(R.id.ed_name);
} public void QureyData(View view) {
String name = null;
Cursor cursor = getContentResolver().query(Uri.parse(uri), null, null, null, null); while (cursor.moveToNext()) {
name = cursor.getString(cursor.getColumnIndex("name"));
}
mEditText.setText(name);
} public void InsertData(View view) {
String editName = mEditText.getText().toString();
ContentValues values = new ContentValues();
values.put("name, editName);
Uri result = getContentResolver().insert(Uri.parse(uri), values);
// 注意 ： 此条添加上才ContentObserver可以监听数据库改变
getContentResolver().notifyChange(Uri.parse(uri),null);
long parseid = ContentUris.parseId(result);
if (parseid > 0) {
Toast.makeText(MainActivity.this, "保存成功", Toast.LENGTH_LONG).show();
mEditText.setText("");
}
}
}注意 ：
至此，自定义ContentProvider的使用方法已经实现。
2. 获取联系人信息的方法
Android 系统自带一下ContentProvider ,比如 联系人packages\providers 下的内容
Android 系统Provider.png
本段主要实现获取系统联系人(ContactProvider)提供的一些信息
获取联系人实现方法
public class ContactListActivity extends Activity { private static final String tag = "ContactListActivity"; private ListView lv_contact_list; private List<HashMap<String, String>> mContactList = new ArrayList<HashMap<String, String>>(); private Handler mHandler = new Handler() { public void handleMessage(android.os.Message msg) { // 给数据适配器设置数据
MyAdapter myAdapter = new MyAdapter();
TextView emptyView = new TextView(getApplicationContext());
emptyView.setLayoutParams(new LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
emptyView.setText(getResources().getString(
R.string.please_add_contanct));
emptyView.setVisibility(View.GONE);
emptyView.setTextColor(Color.BLACK);
emptyView.setTextSize(20);
emptyView.setGravity(Gravity.CENTER);
((ViewGroup) lv_contact_list.getParent()).addView(emptyView);
lv_contact_list.setEmptyView(emptyView);
lv_contact_list.setAdapter(myAdapter);
};
}; @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact_list);
initUI();
initData();
} /**
* 从系统数据库中获取联系人数据,权限,读取联系人
*/
private void initData() { new Thread() { public void run() { // 1,获取内容解析器(访问地址(后门))
ContentResolver contentResolver = getContentResolver(); // 2,对数据库指定表进行查询操作
Cursor cursor = contentResolver.query(Uri
.parse("content://com.android.contacts/raw_contacts"), new String[] { "contact_id" }, null, null, null); // 3,判断游标中是否有数据,有数据一直度
while (cursor.moveToNext()) {
String id = cursor.getString(0);
Log.i(tag, "id = " + id);// 1,2,3
// 4,通过此id去关联data表和mimetype表生成视图,data1(数据),mimetype(数据类型)
Cursor indexCursor = contentResolver.query(
Uri.parse("content://com.android.contacts/data"), new String[] { "data1", "mimetype" }, "raw_contact_id = ?", new String[] { id }, null);
HashMap<String, String> hashMap = new HashMap<String, String>(); // 5,游标向下移动获取数据过程
while (indexCursor.moveToNext()) {
String data = indexCursor.getString(0);
String type = indexCursor.getString(1); // Log.i(tag, "data = "+data);
// Log.i(tag, "type = "+type);
if (type.equals("vnd.android.cursor.item/phone_v2")) { // data就为电话号码
hashMap.put("phone", data);
} else if (type.equals("vnd.android.cursor.item/name")) { // data 为联系人名字
hashMap.put("name", data);
}
}
indexCursor.close();
mContactList.add(hashMap);
}
cursor.close(); // 告知主线程集合中的数据以及准备完毕,可以让主线程去使用此集合,填充数据适配器
mHandler.sendEmptyMessage(0);
};
}.start();
} private void initUI() {
lv_contact_list = (ListView) findViewById(R.id.lv_contact_list);
lv_contact_list.setOnItemClickListener(new OnItemClickListener() { @Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // 1,position点中条目的索引值,集合的索引值
String phone = mContactList.get(position).get("phone"); // 2,将此电话号码传递给前一个界面
Intent intent = new Intent();
intent.putExtra("phone", phone);
setResult(0, intent); // 3,关闭此界面
finish();
}
});
} class MyAdapter extends BaseAdapter { @Override
public int getCount() { return mContactList.size();
} @Override
public HashMap<String, String> getItem(int position) { return mContactList.get(position);
} @Override
public long getItemId(int position) { return position;
} @Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder holder; if (convertView == null) {
holder = new Holder(); // 1,生成当前listview一个条目相应的view对象
convertView = View.inflate(getApplicationContext(),
R.layout.list_item_contact, null); // 2,找到view中的控件
holder.tv_name = (TextView) convertView
.findViewById(R.id.tv_name);
holder.tv_phone = (TextView) convertView
.findViewById(R.id.tv_phone);
convertView.setTag(holder);
} else {
holder = (Holder) convertView.getTag();
} // 3,给控件赋值
holder.tv_name.setText(getItem(position).get("name"));
holder.tv_phone.setText(getItem(position).get("phone")); return convertView;
}
} class Holder { public TextView tv_name; public TextView tv_phone;
}
}ListView 显示布局如下
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/lv_contact_list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView></LinearLayout>item 布局如下：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:orientation="vertical" >
<TextView
android:text="联系人名称"
android:id="@+id/tv_name"
android:textSize="18sp"
android:textColor="@color/black"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:text="联系人电话号码"
android:id="@+id/tv_phone"
android:textSize="18sp"
android:textColor="@color/grey"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/></LinearLayout>注意： 获取联系人需要权限
至此，已经可以获取并显示联系人信息。
3.获取短信内容的方法
短信内容数据也是Android系统提供的，获取方法如下：
获取方法如下
package com.programandroid.ContentProvider;import android.app.Activity;import android.content.ContentResolver;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.net.Uri;import android.os.Bundle;import android.support.v4.widget.CursorAdapter;import android.util.Log;import android.view.View;import android.view.ViewGroup;import android.widget.ListView;import android.widget.TextView;import com.programandroid.MainActivity;import com.programandroid.R;/*
* MmsListActivity.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/public class MmsListActivity extends Activity { private ContentResolver resolver; private ListView listView; private static final String SMS_URI = "content://sms"; private Cursor cursor; @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mms_list);
listView = (ListView) findViewById(R.id.lv_mms);
resolver = getContentResolver();
} public void GetMMSBtn(View view) { // 插入数据
ContentValues values = new ContentValues();
values.put("address", "136259");
values.put("body", "测试数据中。。。。。");
resolver.insert(Uri.parse(SMS_URI), values); // 查询数据方法
cursor = resolver.query(Uri.parse(SMS_URI), null, null, null, null); // 将数据显示到ListView中
listView.setAdapter(new MyAdapter(MmsListActivity.this, cursor,
CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER));
} @Override
protected void onDestroy() { super.onDestroy(); if (cursor != null) { // 关闭cursor
// cursor.close();
}
} class MyAdapter extends CursorAdapter { public MyAdapter(Context context, Cursor c, int flags) { super(context, c, flags);
} // 创建一个视图，引入listview要展示的子视图
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) { return getLayoutInflater().inflate(R.layout.list_item_mms, null);
} // 绑定数据的方法
@Override
public void bindView(View view, Context context, Cursor cursor) {
TextView tvNumber = (TextView) view.findViewById(R.id.tv_number);
TextView tvContent = (TextView) view.findViewById(R.id.tv_content);
TextView tvState = (TextView) view.findViewById(R.id.tv_state);
TextView tvDate = (TextView) view.findViewById(R.id.tv_date);
TextView tvId = (TextView) view.findViewById(R.id.tv_id);
TextView tvRead = (TextView) view.findViewById(R.id.tv_read);
String number = cursor.getString(cursor.getColumnIndex("address"));
String body = cursor.getString(cursor.getColumnIndex("body"));
String date = cursor.getString(cursor.getColumnIndex("date")); int read = cursor.getInt(cursor.getColumnIndex("read")); int id = cursor.getInt(cursor.getColumnIndex("_id")); int type = cursor.getInt(cursor.getColumnIndex("type")); if (read == 0) {
tvRead.setText("短信状态：未读");
} else {
tvRead.setText("短信状态：已读");
}
tvNumber.setText("手机号：" + number);
tvContent.setText("短信内容：" + body);
tvDate.setText("接收短信时间:" + date);
tvId.setText("短信Id：" + id); if (type == 1) {
tvState.setText("短信状态：已接收");
} else {
tvState.setText("短信状态：已发送");
}
}
}
}ListView 布局如下
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/lv_mms"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>item 布局如下：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/tv_number"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_state"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_read"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" /></LinearLayout>4. ContentResolver 内容解析者
ContentResolver主要是通过URI调用getContentResolver()获取ContentProvider 提供的数据接口，进而进行增删改查等操作。
// 查询
Cursor cursor = getContentResolver().query(Uri.parse(uri), null, null, null, null);// 插入数据到指定 URI 中
getContentResolver().insert(Uri.parse(uri), ContentValues);5.ContentObserver 内容观察者
ContentObserver 内容观察者通过指定URI 监听ContentProvider数据是否改变。
自定义 ContentObserver 内容观察者
1.注册ContentObserver 内容观察者 registerContentObserver
/**
* 监听ContentProvider数据库变化
*/
private void ContentObserverDatabase() { // [1]注册内容观察者
Uri uri = Uri.parse("content://ProgramAndroid/person"); // false 观察的uri 必须是一个确切的uri 如果是true
getContentResolver().registerContentObserver(uri, true, new CustomContentObserver(new Handler()));
}2.继承 ContentObserver 实现 onChange方法
package com.programandroid.ContentProvider;import android.database.ContentObserver;import android.os.Handler;/*
* CustomContentObserver.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/public class CustomContentObserver extends ContentObserver { /**
* @param handler
*/
public CustomContentObserver(Handler handler) { super(handler); // TODO Auto-generated constructor stub
} // 当我们观察的uri发生改变的时候调用
@Override
public void onChange(boolean selfChange) {
System.out.println(" 数据库被操作了 "); super.onChange(selfChange);
}
}注意 ：
至此自定义内容观察者已经实现完成
调用ContentObserver 监听短信数据改变
public class MainActivity extends Activity { @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); //[1]注册一个内容观察者
Uri uri = Uri.parse("content://sms/");
getContentResolver().registerContentObserver(uri, true, new MyContentObserver(new Handler()));
} private class MyContentObserver extends ContentObserver{ public MyContentObserver(Handler handler) { super(handler);
} //当观察的内容发生改变的时候调用
@Override
public void onChange(boolean selfChange) {
System.out.println(" 短信的数据库发生了改变"); super.onChange(selfChange);
}
}6. ContentProvider ContentResolver ContentObserver 三者关系
三者关系图如下
关系图.png
至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢！
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